add Close() and Closed() to ChanValue

R=r
DELTA=60  (56 added, 3 deleted, 1 changed)
OCL=33868
CL=33872
diff --git a/src/pkg/runtime/runtime.h b/src/pkg/runtime/runtime.h
index c346c69..1e89a45 100644
--- a/src/pkg/runtime/runtime.h
+++ b/src/pkg/runtime/runtime.h
@@ -73,7 +73,7 @@
  * amd64: allocated downwards from R15
  * x86: allocated upwards from 0(FS)
  * arm: allocated upwards from R9
- * 
+ *
  * every C file linked into a Go program must include runtime.h
  * so that the C compiler knows to avoid other uses of these registers.
  * the Go compilers know to avoid them.
@@ -491,5 +491,7 @@
 Hchan*	makechan(uint32, uint32, uint32);
 void	chansend(Hchan*, void*, bool*);
 void	chanrecv(Hchan*, void*, bool*);
+void	chanclose(Hchan*);
+bool	chanclosed(Hchan*);
 
 void	ifaceE2I(struct InterfaceType*, Eface, Iface*);